Which part of nephron of the human kidney is responsible for filtration of blood for excretion?
- (a)Collecting duct
- (b)Renal vein
- (c)Ureter
- (d)Bowman's capsule
Correct — D, Bowman's capsule. Each nephron begins with a cup-shaped Bowman's capsule enclosing a tuft of capillaries called the glomerulus. Blood enters the glomerulus under pressure and its small molecules (water, glucose, salts, urea) are forced out into the Bowman's capsule — this ultrafiltration is the blood-filtering step of excretion. The rest of the nephron then reabsorbs the useful substances.
- (a)Collecting duct — The collecting duct comes at the END of the nephron; it gathers and concentrates the already-formed urine (final water reabsorption). It does not filter the blood.
- (b)Renal vein — The renal vein is a blood vessel that carries the filtered (cleaned) blood AWAY from the kidney — it is not part of the nephron and performs no filtration.
- (c)Ureter — The ureter is the tube that carries finished urine from the kidney to the urinary bladder; it lies outside the nephron and does not filter blood.
The nephron is the structural and functional (filtering) unit of the kidney; each human kidney has about a million of them. A nephron has a Malpighian body — a glomerulus (capillary tuft) cupped inside a Bowman's capsule — and a long renal tubule. Excretion happens in three steps: ultrafiltration at the glomerulus/Bowman's capsule, selective reabsorption along the tubule, and tubular secretion.
Four kidney-related structures are listed but only one does the actual filtering. Trace the flow: blood in -> glomerulus + Bowman's capsule filter it -> tubule reabsorbs the useful part -> collecting duct concentrates -> ureter carries urine out. Only the Bowman's capsule/glomerulus sits at the filtration step; the vein, ureter and collecting duct all handle material after filtration.
- Filtration (ultrafiltration) of blood occurs at the glomerulus inside the Bowman's capsule — the first step of urine formation.
- The nephron is the structural and functional unit of the kidney; about 1 million per human kidney.
- After filtration, the renal tubule reabsorbs glucose, most water and salts back into the blood.
- Order after filtration: Bowman's capsule -> renal tubule (reabsorption) -> collecting duct -> ureter -> bladder.
- Confusing the renal artery/vein (blood vessels serving the kidney) with parts of the nephron.
- Thinking the ureter or collecting duct filters blood — they only carry or concentrate urine already formed.
Kidney/nephron is asked as 'which part filters blood', 'the functional unit of the kidney', or match-the-part-to-its-function.
With reference to the work of human kidney, consider the following statements: 1. After the waste is removed in the kidney, the cleaner blood is sent back through renal artery. 2. From Bowman's capsule, the filtered liquid passes through tiny tubes where much of the glucose is reabsorbed and sent back to the blood in the renal vein. Which of these statements is/are correct?
- (a) Only 1
- (b) Only 2
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(b) Only 2
Directly on nephron function — statement 2 describes ultrafiltration at the Bowman's capsule followed by glucose reabsorption in the tubule (correct); statement 1 is wrong because cleaned blood leaves via the renal vein, not the renal artery.
- practice — not a real PYQ
The structural and functional unit of the human kidney is the
- (a)Neuron
- (b)Nephron
- (c)Alveolus
- (d)Nephridium
Answer(b) Nephron — the kidney's blood-filtering unit (about a million per kidney).
- practice — not a real PYQ
In a nephron, most of the glucose in the filtrate is reabsorbed into the blood in the
- (a)Bowman's capsule
- (b)Renal tubule
- (c)Ureter
- (d)Collecting duct
Answer(b) Renal tubule — selective reabsorption of glucose and water follows filtration.